1. Field of the Invention
The present invention relates to low-substituted hydroxypropyl cellulose to be added to impart preparations with disintegrability or a binding property upon their production in the pharmaceutical or food field; and a production process thereof.
2. Description of the Related Art
In the pharmaceutical or food field, solid preparations composed alone of an active ingredient are accompanied with the problems that even the administration of the medicament cannot bring about sufficient effects because they lack in disintegrability, or they cannot retain their shapes when formed into tablets or granules because of a poor binding property. In such a case, addition of low-substituted hydroxypropyl cellulose to the preparations can impart them with disintegrability or a binding property.
In addition to this low-substituted hydroxypropyl cellulose, calcium salt of carboxymethyl cellulose, crosslinked sodium carboxymethylcellulose, crosslinked polyvinylpyrrolidone, and carboxymethyl starch can be given as examples usable for the above-described purpose. Low-substituted hydroxypropyl cellulose has an advantage that since it is nonionic, it is not easily deteriorated by the reaction with an ionic substance.
There are a method of manufacturing tablets by dryly blending low-substituted hydroxypropyl cellulose powder, a medicament and the other ingredients such as excipient and then tableting the resulting mixture; and a method of forming granules by kneading the above-described ingredients with water or an aqueous solution of a water soluble binder and then granulating the resulting mixture. The low-substituted hydroxypropyl cellulose is a medicinal additive included in Japanese Pharmacopoeia and use of it as a medicinal additive has already been described in Japanese Patent Publication (JP-B) No. 46-42792/1971 and Japanese Patent Publication (JP-B) No. 57-53100/1982.
The low-substituted hydroxypropyl cellulose is a mixture of fibrous and granular parts in the powdery form and a binding property required for formation of tablets is said to result from the entanglement of the fibrous part of the mixture. An increase in the content of this fibrous part in order to heighten the binding property, however, makes the powder bulky and lowers its fluidity. In the method of dryly blending low-substituted hydroxypropyl cellulose, a medicament and the other ingredients including excipient and then tableting the resulting mixture, which method is generally called “dry direct compression”, this low fluidity causes problems that tableting cannot be performed because the mixture does not come out from the hopper of a tableting machine, or even if tableting can be performed, a weight variation of the tablets becomes excessively large. In Japanese Patent Provisional Publication (JP-A) No. 7-324101/1995, disclosed is low-substituted hydroxypropyl cellulose having a swelling ratio of 100% or greater at an angle of repose of 45° or less. This cellulose has improved fluidity, but involves a problem that a reduction in the amount of a fibrous part leads to lowering in a binding property.